Serially improved Gaussian-type orbitals for molecular calculations containing third-row atoms

Serially improved Gaussian-type orbitals for molecular applications (SIGMA) basis sets have been developed for third-row elements, spanning from sodium to argon. This methodology, originally established for first- and second-row atoms, has been extended to produce both standard and augmented basis sets with sizes ranging from double-zeta to quadruple-zeta. The SIGMA basis sets yield atomic and molecular energies that are consistently lower than those obtained using Dunning basis sets with the same number of contracted functions. This advantage is observed for various computational methods, including Hartree-Fock, M\o{}ller-Plesset perturbation theory, single-double configuration interaction, and coupled-cluster approaches. Comparative analyses of SIGMA and other basis sets are presented, showing their performance in calculating atomic energies and a range of molecular properties.